It is desirable to devise a permanent magnet excited mechanism for transmitting variable torque in drive applications. Specifically there is a need to couple constant speed devices such as motors or engines to variable output speed and torque devices such as pump impellers, fans, propellers, wheels, etc.
Transmission devices including various eddy current clutches have been in use for some time in various forms. An examination of the prior art shows that these eddy current devices are limited to three general types
Current fixed gap permanent magnet disk clutches are limited in their ability to transmit large amounts of torque and are constructed in a manner which causes instability at higher speeds. These limitations relegate the practical application of these devices to low speed, low horsepower application.
Eddy current clutches that use DC current to generate and vary the flux density in a fixed gap mechanism. These devices are available in a wide range of horse power but are expensive, complicated and require a DC current and control to induce the torque. There are applications where the DC current is not desirable or where the apparatus for controlling the torque producing currents are unreliable.
Current variable gap permanent magnet disk clutches are limited in their ability to transmit large amounts of torque and are constructed in a manner which causes instability at higher speeds. These limitations relegate the practical application of these devices to low speed, low horsepower application.
The apparatus described utilizes recent developments in magnetic material technology, in conjunction with architecture designed for mechanically stable operation. This will allow the apparatus to be used in a full range of power transmission applications including high horsepower applications. The configuration of the device also makes it stable and able to operate at higher input speeds, which are natively present in some motors and engines,
The described apparatus is a device that uses permanent magnets and conductors arranged in an optimal manner to generate the magnetic flux in a power transmission drive.
The object of this invention is to present a modification to the Inductive magnetic circuit utilizing an alternative orientation of the electro-conductive rotor design which will have a disk shape (plate) construction with an outer ring and inner ring of electro-conductive material surrounded by steel, assembled with rotor bars connecting the inner and outer rings (end rings) radially (i.e., from the inside ring to the outside ring). The bars can be constructed of various shapes (i.e., round, square, etc.) connecting them as required for adjustment of the torque profile developed by the device.
The Magnet rotor assembly would also have the same radial disk shape forming an array of magnets oriented from the inside of the rotor disk to the outside and have the magnet polarity opposed at adjacent magnets and magnetized through the thickness of the rotor plate. Note that one (1) magnet rotor would be surrounded by two (2) inductive rotor assemblies (i.e., one on both sides of the magnet rotor); thereby allowing more flux/power to be transmitted during operation.
Our testing has revealed that our inductive coupling with the rotor bar construction, has an inherent ‘soft-start’ capability during starting. This allows a high inertia load to be accelerated by a motor (or other torque/power source) from rest to full torque at no more than 150% of the rated torque of the coupling. This performance benefit also works to limit torque at any load condition to no more than 150% torque and to also dampen out torque pulsations (i.e., torsional vibration) by the same limits. This would benefit all types of power transmission systems that have high starting toques or the possibility of high spike loading that can cause damage.
The instant invention's inductive magnetic circuit geometry can also be utilized as Dynamometers for braking and tensioning. This would be accomplished by locking the inductive rotor and installing addition cooling piping inside the rotor to dissipate the braking or tensioning/slip heat. Both brake systems and tensioning systems would benefit by the fact that there are no components to wear out (i.e., brake pads, etc.).
An additional capability of tensioning would be torque limiting during rotation of valves or other such devices. This benefit would eliminate the chance that a valve stem/shaft could be broken during the closing process (i.e., if debris is caught in the valve body during closing). This could be called: ‘Inductive Limit Torque’.